Previous clinical studies with OZ439 have shown variable PK and a food effect. One hypothesis is that this may be related to a 'common ion effect' leading to precipitation of the drug as a less soluble hydrochloride salt in the stomach, resulting in variable absorption of the drug. This study is designed to investigate the possibility of improving the PK profile by delivering the drug directly to the PSB, thereby bypassing the stomach. The study will compare a previously dosed PIB formulation with oral delivery of a nanoparticulate as a caplet formulation. The same caplet formulation containing nanoparticulate will be administered to the PSB via the Enterion capsule.